1. Field of the Invention
The present invention relates generally to a system and method for connecting a cellular telephone to a computer system, and more specifically to a system and method for connecting a cellular telephone to a personal computer system through a universal serial bus port.
2. Related Art
There is an increasing need for connecting portable computing devices to computer networks, such as the Internet. A very economical way to perform such connections is to make use of existing cellular telephones that are already in use by consumers. Thus, there is a great need for an efficient and economical means for connecting cellular telephones to portable computing devices, such as lap top computers, personal digital assistants (PDAs) and the like.
Several systems for connecting cellular telephones to personal computer systems exist today. The problem is that these current systems are very expensive both from a manufacturing standpoint and from a consumer standpoint. In addition, many of these systems require that the PC manufacture (or OEM) install a unique and proprietary cellular telephone connector to the PC motherboard or other device. Such unique connectors can only be used with specific cell phone cables that are also produced by the PC manufacturer or OEM. Thus, these current solutions prevent users from connecting their cellular telephones to other personal computer systems that lack the specific built-in and proprietary connectors.
Other solutions that are in existence today, for example, make use of a PCMCIA card to connect cellular telephones to personal computer systems. The advantage to using these systems is that they can be attached to any personal computer system that supports the Personal Computer Memory Card International Association (PCMCIA) standard.
However, the problem is that these systems are extremely expensive to manufacture. Furthermore, these devices, although relatively small, are bulky when compared to the size of many PDAs in existence today. Additionally, these devices require a separate proprietary cable in addition to the PCMCIA logic card. Still further, these devices include a micro-controller, which increases the expense, size, weight and power requirements of the device.
Therefore, what is needed is a system and method for connecting a personal computing system to a cellular telephone that is economical, small in size and weight, consumes low power and can be used with a variety of general-purpose computing systems.
Accordingly, the present invention is directed toward an economical system and method for connecting a cellular telephone to a personal computing device, such as a laptop computer or a personal digital assistant (PDA). The present invention can be made extremely small, has very low power requirements and is economical to manufacture. Furthermore, the present invention can be used with a variety of general-purpose computing systems.
In one embodiment of the present invention, a mobile phone interface (MPI) is molded between the ends of a Universal Serial Bus (USB) cable. One end of the USB cable is plugged into a standard USB port on any personal computing device that supports the USB standard. The other end of the USB cable is plugged into a cellular telephone.
The MPI comprises several logic components that are controlled by software installed on the personal computing system. Preferably, the MPI is implemented using integrated circuit technology such as an application-specific integrated circuit (ASIC) or the like. In this fashion, the MPI can be made extremely small and unobtrusive to the user. In fact, in a preferred embodiment, the MPI is not much wider than the USB cable itself.
The portability of the MPI is a distinct advantage of the present invention over current systems. In addition, the adaptability, (i.e. the ability to use the present invention with any personal computer that supports USB), is another distinct advantage of the present invention. Another advantage of the present invention is that it makes use of the attached computer system to provide the control for the MPI via software, thereby lowering the cost, size and power requirements of the USB adapter.
In one embodiment, the MPI comprises a USB serial interface engine (USB SIE), a digital translation block (DTB) and a cellular phone interface. The cellular phone interface component is used to provide electrical connections to the signals within the supported cellular telephone. Typically, the configuration of the cellular phone interface is in accordance with cellular phone interface standards. An example of such a standard is the NTT DoComo standard, which provides standard interfaces for particular cellular telephone systems in Japan. The advantage to using such standards is that the telephone interface connections do not vary between cellular handset manufacturers.
The DTB component of the present invention performs synchronous and asynchronous data transfer functions in accordance with the particular protocol implemented for each specific embodiment of the present invention. In addition, a typical embodiment includes data buffers to buffer the data between the USB bus and the cellular phone system. The USB serial interface engine performs serialization and de-serialization of USB transmissions as well as implementing the necessary communication protocol and set-up procedures in accordance with the USB standards.
Software for controlling the MPI and for interfacing between the application program running on the computer system and the MPI, is installed on the personal computer system. The software comprises a communication control stack, a hardware access driver and an external plug-in module. The communication control stack comprises an AT parser for parsing standard Hayes AT commands, a call control module for controlling the transfer of data and a number of internal plug-in protocol modules. In addition an external plug-in module is provided. The external plug-in module comprises an external protocol stack and may have its own AT and command parsers.
The external protocol stack comprises a control path and a data path. The control path is used to process control and status data and the data path is used to process communications data. The control path comprises a high level interface, a control stack and a low level interface. Similarly, the data path comprises a high level interface, a data stack and a low level interface.
The high level interfaces communicates with the communication control stack and the low lever interfaces communicate with the hardware access driver, which is closely coupled to the hardware in the MPI. The hardware access driver is interrupt-driven based on the hardware interrupt requests generated by the MPI. The control stack is used to format and store control and status data. The format of the control and status data is in accordance with the particular protocol being implemented by the external protocol stack.
Similarly, the data stack is used to format and store communications data. The format of the communications data is in accordance with the particular protocol being implemented by the external protocol stack.